Sinker mechanism for knitting machines



Jan. 25, 1966 A. w. ROEDEL 3,230,742

SINKER MECHANISM FOR KNITTING MACHINES Filed April 5, 1964 TlE- l Z6 Z322 35 36 20 3. I5 25 /6 INVENTOR A/beri l V Paeoe/ ATTORNEY.

United States Patent 3,230,742 SINKER MEGHANISM FGR- KNITTING MACHINESAlbert Roedel, North Asheboro, N;C., assignor to;

This invention relates, to circular knitting machines and moreparticularly to the sinker mechanism of such machines.

In circular knitting machines the sinkers are mounted in radiallyextendingslots for movement, in cooperation with stitch drawingmovements of the needles, in inner and. outer sinker rings which aresecured to the needle cylinder of the machine for rotation therewith.Conventional ly, the sinkers are constructed ofhardjened steel and theinner sinker ring, which both guides and supports the inner ends of thesinkers over which yarn stitches are drawn by the needles, is alsoconstructed of steel; The inner sinker ring i's also provided'with. anouter peripheral surface which is adapted to slidably support the upperends of the needles during their stitch drawing movements.

During normal operation of the machine the needles are lowered from, ahigh yarn taking level to measure or draw yarn for new stitches over theplatforms or knockover surfaces of the sinkers and to knock off thepreviously formed stitches from the needles. As the needles reach theirlowest stitch drawing position and while the newly drawn stitchescontinue to exert a slight downward pressure on the platforms of thesinkers, the sinkers are advanced inwardly to tension the, previouslyformed stitches to the backs of the. needles and; to hold the newstitches, as the needles are raised to. clear the new stitches prior tothe next yarn taking and. stitch1 drawing operation of the needles,Wln'leboth the needles and sinkers cause gradual wear in the surfaces ofthe inner sinker ring engaged thereby, the wear in the bottoms of thesinker slots is the most critical since it, changes the, verticalrelation between the platforms of thesinkers and. the needles as theneedles drawn yarn for the new stitches. When this wear in the bottomsof the sinker slots reachesv a point that it affects the lengths of thestitches and causes the formation of defective fabric, the inner sinkerring must be discarded and replaced by a new ring.

Heretofore, in order to avoid the frequent discarding of worn parts, ithas been proposed to recondition the inner sinker ring by removing aportion of the material of the ring beneath the slots and replacing theremoved material by a hardened steel insert. While this insert acted torestore the bottom surfaces of the sinker slots to their normalcondition wear Occurring on other portions of the inner sinker ringengaged by the sinkers and needles eventually necessitated replacementof the inner sinker ring.

It is an object of the invention to provide the inner sinker ring of acircular knitting machine with a replaceable insert to renew Wornportions of the sinker ring which will eliminate the above noted andother objections to prior proposals.

Another object of the invention is to replace the worn portions of theinner sinker ring of the sinker mechanism of a circular knitting machinewith an insert of synthetic material such as nylon or the like which hasa greater resistance to wear than the original metallic material of theinner sinker ring.

A further object of the invention is to provide a metallic inner sinkerring with a replaceable insert portion of synthetic material, the insertportion having slots for guiding the sinkers and a bearing surface forsupporting the needles during operation thereof.

With these and other objects in View, which will become apparent fromthe following detailed description. of

the illustrative and practical embodiment of the invention shownin theaccompanying drawings, the invention comprises the novel elements andfeatures of construction, as more particularly pointed out in theclaims.

In the drawings:

FIG. 1 is a. cross-sectional view through the knitting head of aconventional circular knitting machine having a replaceable insertincorporated in the inner sinker ring; of the knitting head according tothe instant invention; and

FIG. 2 is a top plan view on a reduced scaleof the inner sinker ring.

Referring to FIG. 1 of the drawing, there is, shown a portion of theknitting head of a circular knitting machine including a needle cylinder19 having slots 11 for pivotedlatch needles 12 which are raised andlowered in the slots through knitting movements. in cooperation withsinkers 15' to. form yarns into stitches of tubular fabrics such asstockings and the like, in a conventional manner. The sinkers are guidedfor sliding movements between the; needles in radially extending slots16 formed in an outer sinker ring 17 secured to the outer surface of theneedle cylinder It at the upper end thereof and in aligned; slots 20formed in an inner sinker ring 21 secured in adjusted position to aninner surface of the needle cylinder. The inner sinker ring 21 isprovided with an outer peripheral bearing surface 22 for slidablysupporting the needles 12 during knitting movements of the needles. Thesinkers 15 are provided with butts 23 for engagement in a cam groove 25in a sinker cap 26, the cam groove acting on the butts 23 to advance andretract the sinkers in timed relation to the operation of the needles.The sinker cap 2e has a depending flange 27 having an inner bearingsurface 3d closely interfitting an outer bearing surface 31 on the outersinker ring 17 to maintain the sinker cap in accurately centeredrelation to the outer sinker ring.

During operation of the machine to form yarn into stitches, with thesinkers in retracted position as determined by the cam groove 25, theneedles are raised to clear previously formed stitches thereon and aftertaking the yarn are then lowered to measure or draw the yarn for newstitches over platforms or knockover surfaces 32 of the sinkers, and toknock over the previously formed stitches. The sinkers are then advancedinwardly to tension the previously formed stitches to the backs of theneedles and to hold the new stitches before the needles are again raisedto clear the new stitches. During their cooperating stitch formingmovements, the needles 12 and sinkers 15, which are made of hardenedsteel, gradually wear the surfaces of the inner sinker ring, which isalso made of steel, engaged by the needles and sinkers. When this wearreaches a point that it affects the length of the stitches and causesdefective fabric, the inner ring must be discarded and replaced by a newring.

In order to greatly increase the wearing life of the inner sinker ring21 and to avoid discarding the entire ring when excessively wornaccording to the instant invention, the upper end of the ring ismachined to remove the slotted portion and the outer diameter of thering is turned down to form an upper flange 34 as indicated in FIG. 1,and replaced by a replaceable insert 35. The insert is in the form of aring (FIG. 2) which is initially machined only to form a recess tointerfit the reshaped upper flange 34 of the ring 21 and the insert isthen bonded to the upper and outer peripheral surfaces of the flange ofthe ring by a layer 36 of adhesive. The insert is then machined to thesame shape as the original ring and reslotted to receive the sinkers.

Preferably the insert 35 is made of a material such as a syntheticlinear condensation polymer of the type generally referred to as nylonor any other synthetic material having similar characteristics. Thenylon provides an ideal bearing material for both the metallic needlesand sinkers that resist wear and greatly increases the life of theremaining metallic portion of the inner sinker ring.

The adhesive employed for the layer 36 is of a type that is thermosetting and that will adhere or bond itself to both the metallicmaterial of the inner sinker ring 21 and the nylon material of theinsert. In carrying out the instant invention the adhesive layer thatwas found to provide the most desirable results includes two well knowncommercial adhesives, Cycle-weld which is a compound ofphenol-formaldehyde and a synthetic rubber such as Buna N made byChrysler Corp. and Cascophene No. RS216 which is a resorcinal-phenolcompound made by the Borden Co.

In preparing the parts for jointure the interfitting surfaces of theinsert 35 and inner sinker ring 21 are slightly roughened and thoroughlycleaned of all dirt and other foreign matter. The metal surfaces ofinner sinker ring are coated with the Cycle-weld compound which ispermitted to air dry for at least fifteen minutes. A second coating ofthe Cycle-weld is then applied to the first coating and permitted to airdry for approximately fifteen minutes after which it is baked forfifteen minutes at 170 and for thirty minutes at 340 to remove all ofthe solvent. A coating of Cascophene is then applied over the coating ofCycle-weld and the surfaces of the insert and the latter coatings areallowed to air dry for a few minutes after which the insert 35 isassembled and clamped to the inner sinker ring 21. The parts arepermitted to cure for approximately forty-eight hours to completely setthe cement and permit the cement to reach its maximum bonding strength.The insert is then machined to the required shape and slotted as aboveset forth.

The instant invention is applicable to both new and reconditioned innersinker rings and results in a longer operating life of the ring.Furthermore, the insert itself when becoming worn may be readilyreplaced which permits the continued use of the metallic portion of theinner sinker ring.

Having described the invention in detail it will be .understood thatthese details need not be strictly adhered to and that various changesand modifications may be made falling within the scope of the inventionas defined in the following claims.

What is claimed is:

1. In a circular knitting machine having a rotatable needle cylinder,slots in said cylinder, needles movable through stitch drawing movementsin said slots, sinkers cooperating with said needles, an outer sinkerring secured to said cylinder, an inner sinker ring secured to saidcylinder and having an outer peripheral surface for supporting saidneedles during said stitch drawing move-. ments thereof, radiallyextending slots for said sinkers in said outer and inner sinker rings,said inner sinker ring having a nonmetallic portion of synthetic linearcondensation polymer in which said slots for said sinkers and said outerperipheral supporting surface for said needles are formed, and ametallic portion which is secured to said cylinder, said metallicportion of said inner sinker ring having an upper flange and saidnon-metallic portion of said inner sinker ring having a recess thereinto receive said upper flange of said metallic portion.

2. An inner sinker ring for a circular knitting machine having anon-metallic portion of synthetic linear condensation polymer and ametallic portion, slotsin said nonmetallic portion for supportingsinkers for radially sliding movements thereof, a vertical extendingperipheral surface on said non-metallic portion for supporting needlesduring stitch drawing movements thereof, a recess in 'said non-metallicportion, an upper flange on said metallic portion of said sinker ringadapted to be received in said recess on said non-metallic portion, anda layer of adhesive between the upper and outer peripheral surfaces ofsaid upper flange and the surfaces of said. recess to bond saidnon-metallic portion to said metallic portion.

References Cited by the Examiner UNITED STATES PATENTS 2,271,852 2/1942vBrumbach 66110 2,384,451 9/1945 Brumbach 66110 2,710,528 6/1955 Cobert66-110 2,931,198 4/1960 Bitzer 66-410 2,951,355 9/1960 Bryant 66-110FOREIGN PATENTS 819,686 9/1959 GreatBritain.

825,637 12/1959 GreatBritain.

861,066 2/1961 Great Britain.

RUSSELL C. MADER, Primary Examiner.

1. IN A CIRCULAR KNITTING MACHINE HAVING A ROTATABLE NEEDLE CYLINDER,SLOTS IN SAID CYLINDER, NEEDLES MOVABLE THROUGH STICH DRAWING MOVEMENTSIN SAID SLOTS, SINKERS COOPERATING WITH SAID NEEDLES, AN OUTER SINKERRING SECURED TO SAID CYLINDER, AN INNER SINKER RING SECURED TO SAIDCYLINDER AND HAVING AN OUTER PERIPHERAL SURFACE FOR SUPPORTING SAIDNEEDLES DURING SAID STITCH DRAWING MOVEMENTS THEREOF, RADIALLY EXTENDINGSLOTS FOR SAID SINKERS IN SAID OUTER AND INNER SINKER RINGS, SAID INNERSINKER RING HAVING A NONMETALLIC PORTION OF SYNTHETIC LINEARCONDENSATION POLYMER IN WHICH SAID SLOTS FOR SAID SINKERS AND SAID OUTERPERIPHERAL SUPPORTING SURFACE FOR SAID NEEDLES ARE FORMED, AND AMEATLLIC PORTION WHICH IS SE-